Rapid 3-D Resistivity inversion for complicate model

While conjugate gradient(CG) relaxation technique is used to solve the inverse equations and Rodi method is introduced to compute the Jacobi matrix G,only one forward calculation is required in each inversion iteration,thus the 3-D resistivity inversion is computed much quickly.Additionally,by avoiding huge storage for G and G^TG and imposing a smoothness constraint on model,we make a solid base of 3-D resistivity inversion for the complicate structure.